Annia Rodríguez-San Pedro

Acoustic identification of four species of bats (Order Chiroptera) in central Chile

Echolocation calls of four species of insectivorous bats of central Chile were recorded and characterized to determine vocal signatures that allow their identification in the field. Pulses of Tadarida brasiliensis were characterized by the highest duration and the lowest values for all frequencies, which do not overlap those of the remaining species. Tadarida emits narrowband, shallow frequency-modulated search calls. All three vespertilionid species studied (Histiotus montanus, Lasiurus varius and Myotis chiloensis) showed similar echolocation design to one another, consisting of a downward frequency modulation at the beginning of the signal followed by a narrowband quasi-constant frequency component; however, their calls differ by their spectral characteristics. Discriminant function analysis of six acoustic parameters (duration, initial frequency, slope frequency modulation, peak frequency, minimal and maximal frequencies) gave an overall classification of 87.4%, suggesting species could be correctly classified based on echolocation calls. Call duration and minimal frequency were the variables most important for species identification.

The relative influence of forest loss and fragmentation on insectivorous bats: does the type of matrix matter?

ContextDisentangling the relative effects of forest loss versus fragmentation on species distribution and abundance is crucial for adopting efficient biodiversity conservation actions, which could change with the nature of the landscape matrix.ObjectivesWe tested the moderating effect of landscape matrix on insectivorous bats response to forest loss and fragmentation.MethodsWe conducted acoustic surveys at forest patches surrounded by either an agricultural-dominated matrix or a pine-dominated matrix. We related bat activity to forest amount and the number of forest patches at multiple spatial scales, and compared their effects between landscape matrices.ResultsBat activity was associated with both predictors, however their effects varied with the matrix type. In agricultural landscapes, as the amount of forest increased, the activity of Histiotus montanus, Lasiurus cinereus and Tadarida brasiliensis increased, while activity of Myotis chiloensis decreased. Similarly, as fragmentation increased, the activity of Lasiurus varius and M. chiloensis increased, while activity of H. montanus decreased. In production-forest landscapes, only H. montanus decreased its activity with increasing forest amount. In contrast, activity of L. cinereus, M. chiloensis and T. brasiliensis increased with increasing fragmentation. Forest amount was a stronger predictor for agricultural landscapes than for production-forest landscapes, suggesting that low contrast matrices can mitigate the effects of forest loss.ConclusionsFragmented landscapes with native forest patches surrounded by a low contrast matrix may support a higher activity of insectivorous bats. Management efforts in fragmented landscapes should aim to decrease the patch-matrix contrast, which will mitigate the effects of forest loss on bats.

The heterogeneity and composition of agricultural landscapes influence native and exotic coccinellids in alfalfa fields

The current trend toward simplification of agricultural landscapes, as well as the associated loss of perennial cover types, can decrease landscape heterogeneity and also natural enemy abundance and diversity, favouring exotic species. We evaluated the effects of agricultural landscape composition and heterogeneity at two different spatial scales (radii of 250 and 1000 m), on the diversity and abundance of native and exotic coccinellids, associated with alfalfa fields located in two regions of Central Chile. Data were analyzed using partial least square regressions, considering the whole coccinellid assemblage and the three most abundant species. In both regions, coccinellid diversity and the abundance and proportion of native coccinellids in alfalfa responded differentially from total abundance and the abundance of exotic coccinellids. The diversity and abundance of coccinellids in alfalfa increased with the compositional and configurational heterogeneity of the landscape. The abundance of both native and exotic coccinellids in alfalfa fields decreased as the area covered by cultivated lands, such as annual crops and orchards, increased. Nevertheless, the responses of native and exotic coccinellids were not consistent among regions, which may be explained by responses of the dominant species in each region. The results of the present study suggest that variables related to a higher intensification of agricultural landscapes (lower compositional and configurational heterogeneity, as well as more annual crops) reduce coccinellid diversity and abundance in alfalfa fields. To maintain a higher abundance and diversity of these natural enemies in alfalfa, more heterogeneous landscapes with less annual crops should be promoted.

Does understory clutter reduce bat activity in forestry pine plantations

Forestry plantations supporting native species exhibit a dense understory, which might reduce bat activity within plantations. We compared bat activity in Monterrey pine plantations with and without an understory in central Chile. Total activity did not differ between plantations with a developed understory and those without it, being higher on-track than off-tracks sites. Trails provide commuting areas for bats within plantations allowing its use regardless of their degree of structural clutter. Promoting understory in plantations provides habitats for bats and might enhance their conservation in human-modified landscapes.

Variation in search-phase calls of Lasiurus varius (Chiroptera: Vespertilionidae) in response to different foraging habitats

Abstract Intraspecific variability in echolocation calls could be an important factor hampering the accurate acoustic identification of species in the field. We studied variations in the echolocation behavior of Lasiurus varius in relation to habitat structure. Echolocation calls of L. varius reflected the degree of clutter present in its foraging areas. Bats foraging in an uncluttered habitat emitted longer and lower-bandwidth calls, with the lowest frequency values, whereas bats foraging in a cluttered habitat broadcast shorter and broadband signals, showing an increase in frequency content of their calls. Discriminant function analysis gave an overall classification of 76% of the calls emitted in the different flight situations. Our results highlight the need for independent recordings at each study area or habitat type to circumvent potential echolocation call variations, particularly in fragmented landscapes.

Distribution extension and new record of Myotis atacamensis (Lataste, 1892) (Chiroptera: Vespertilionidae) in Chile

Myotis atacamensis is a poorly known bat species endemic to the central portion of the pacific coast of South America, where it is known from the province of Lambayeque, Peru (latitude 5° S), to the province of Elqui (latitude 30° S), Chile. Here, we report the first record of M. atacamensis for the province of Choapa (latitude 31° S, Coquimbo Region) in Chile. This is the southernmost record of the species within Chile and South America, extending its geographic range ca. 200 km southward.

Influence of agricultural management on bat activity and species richness in vineyards of central Chile

Agricultural intensification is one of the major causes for the global loss of biodiversity and associated ecosystem services. As an alternative to conventional farming, organic management is considered a way to mitigate some of the negative impacts on biodiversity in agricultural landscapes; however, their benefits for bats are not very conclusive. We investigated the hypothesis that organic farming benefits bats in vineyards by improving conditions for foraging through increased availability of prey. We also hypothesized that bat activity would vary between edges and the interior of vineyards in response to prey availability that in turn would be influenced by agricultural management. Bat activity was quantified along edge and the interior of each vineyard type by using acoustic surveys. In addition, we sampled nocturnal flying insects at each site using light traps. Species richness and overall bat activity were significantly higher in organic than conventional vineyards, with organic edges concentrating the highest bat activity. Our results suggest negative effects of agricultural intensification on insectivorous bats. The high bat activity along edges compared to the interior of vineyards suggest that these structural features of the landscape are important components for bat populations in vineyards, and therefore should be considered within agricultural management in order to promote bat abundance and their role as pest suppressors.